Breast imaging is used to detect breast lesions and especially breast tumours. Once detected, breast tumours can efficiently be medically treated. This entails medical monitoring of patients who undergo breast imaging sessions regularly over the years.
During a breast imaging session, the breast of the patient is compressed between a compression paddle and a breast support of an imaging apparatus and the compressed breast is illuminated by an illumination source, usually X-ray source. The illumination beams, part of which goes through the breast, are then collected by a detector.
Apart from obtaining constant breast thickness and immobilising the breast, breast compression is needed for two purposes.
First, the illumination dose needed for breast imaging decreases with the thickness of the imaged object, here the breast. An excessive illumination dose is harmful to the patient's health. Thus, the illumination dose should be as low as possible, while enabling the breast tissues to be clearly imaged. The more the breast is compressed, the lower the illumination dose, while retaining at least the same quality of the medical image.
Second, the breast imaging system enables acquisition of two-dimensional (2D) medical images on which the breast is projected throughout its thickness. Consequently, the medical images necessarily show a superimposition of breast tissues. An excessive superimposition of breast tissues impairs the diagnosis of the physician because two much information is gathered at the same place on the medical image. For example, breast lesions may be obscured by normal breast tissues (false negatives) or superimposition of normal breast tissues can mimic suspicious lesions (false positives). Compressing the breast makes it possible to spread it over a larger area. Thus, the superimposition of breast tissues is reduced.
Breast compression, while improving the medical image quality and easing the physician's diagnosis, incurs patient's discomfort that can reach pain.
Moreover, studies show that 1 out of 6 women refuse to undergo further breast imaging due to painful past experience (N. Mullai, N. Murugesan, L. Burton, V. Goodin, A. Stout of the Hematology and Oncology Centre, PLLC, Somerset, Ky., ASCO, 2009).
Attempts to relieve pain and improve patient's comfort during an imaging session have been experienced over the years. These include for example providing patients with verbal and/or written information on the breast imaging technic before the session, providing pain relief medication before the session, using breast cushion padded onto the surface of the imaging apparatus or flexible compression paddle to dampen pain, reducing breast compression by the technician operating the imaging apparatus.
P. J. Kornguth, M. R. Conaway and D. C. Sullivan investigated the impact of technician-controlled breast compression and patient-controlled breast compression on pain felt by the patient (P. J. Kornguth et al., Impact of patient controlled compression on the mammography experience, Radiology, 1993, 186(1), pp 99-102). They showed that 34 out of 109 women (31%) claimed less discomfort when they controlled the compression of their own breast in comparison with a compression controlled by a technician, 61 women (56%) claimed no difference as far as pain feeling is concerned and 14 women (13%) claimed that self-controlled breast compression was more painful than technician-controlled breast compression.
Therefore, it has been attempted to give the patients control of the compression of the own breast.
Unfortunately, some extremely sensitive women are reluctant to increase the compression as soon as they feel pain, even at a compression force that for most women is considered as endurable. Consequently, the obtained medical images are of poor quality and the technician has to control back breast compression.
Thus, there is a need for a new breast imaging system and method so that good quality medical images can be obtained while improving patient's comfort during an imaging session.